The invention relates to a voltage measuring device of a high voltage conductor, located in a sealed enclosure filled with a high dielectric strength gas, notably a high voltage metalclad installation, comprising a capacitive divider formed by a high voltage capacitor and a low voltage capacitor connected in series, the high voltage capacitor being located in said enclosure and comprising said conductor and an electrode surrounding said conductor and the low voltage capacitor being located outside said enclosure and being electrically connected to said electrode by a conductor passing through the enclosure wall.
A measuring device of the kind mentioned comprises a low voltage capacitor housed in the enclosure of the metalclad installation, more particularly in direct proximity to the high voltage capacitor. In this way inaccuracies due to temperature and pressure variations, which influence both the high voltage capacitor and the low voltage capacitor housed in the same enclosure, are avoided. The low voltage capacitor is a fragile element and servicing or repairs may be required periodically. In this case, the whole installation has to be taken out of the circuit and drained to give access to this low voltage capacitor. These draining operations, which subsequently require recreation of a vacuum and filling with sulphur hexafluoride, are delicate and complicated.
The object of the present invention is to provide a capacitive divider measuring device allowing easy access to the low voltage capacitor while avoiding variations due to the temperature or pressure of the gas in the installation.